Generally, when a light source device as a tail lamp is provided at a rear part of a vehicle, it may be preferable to dispose the light source device transversely in such a manner as to extend in the vehicle width direction, rather than disposing the light source device longitudinally in such a manner as to extend in the up-down direction in terms of design. However, there is a problem that a vehicle body opening may be narrowed when a light source device is transversely disposed in such a manner as to extend in the vehicle width direction.
In view of the above, Patent Literatures 1 to 4 propose a configuration, in which a light source device is disposed at a periphery of a vehicle body opening, which is formed in a rear part of a vehicle, and the light source device is covered by a lift gate mounted on a vehicle body in such a manner as to openably close the vehicle body opening. The configuration disclosed in Patent Literatures 1 to 4 provides an advantage that it is possible to implement a unique design by differentiating the external appearance of a light source device between when a lift gate is opened and when the lift gate is closed, while securing the width of a vehicle body opening.
When a light source device is covered by a lift gate as described above, a lens member for light adjustment may be provided on the lift gate so that light from the light source device is irradiated in an appropriate range viewable from the vehicle rear side. In this case, particularly when the light source device is functioned as a brake lamp, it is necessary to design the light source device, the lens member, and the layout of these members, taking into consideration visibility from the vehicle rear side so that a predetermined irradiation state is secured.
Conventionally, however, it is a general practice to use a component called as a rear combination lamp. The rear combination lamp is a sub-assembly constituted by a light source and a lens. The sub-assembly is integrally fixed to a vehicle body or a lift gate. In the aforementioned configuration, by appropriately adjusting a positional relationship between a light source and a lens in advance in forming the light source and the lens into a sub-assembly, basically, there is no likelihood that the positional relationship between the light source and the lens may be deviated.
As described above, when a light source device is mounted on a vehicle body, and when a lens member is mounted on a lift gate connected to the vehicle body by a hinge, as compared with the aforementioned configuration of a rear combination lamp, a positional relationship between the light source device and the lens member in a state that the lift gate is closed is likely to be deviated due to a mounting error, a dimension error (positional deviation) of a hinge, or a like factor. Further, repeating an opening/closing operation of a lift gate may cause a deviation in positional relationship between a vehicle body and the lift gate.
As described above, if a positional relationship between a light source device and a lens member deviates when a lift gate is closed, an irradiation state by the lens member may be deviated from an initially intended state when the light source device is turned on.